variolation

variolation, historical method of immunizing healthy individuals against smallpox by infecting them with substance from the sores of patients with a mild form of the disease (variola minor). The disease then usually occured in a less-dangerous form than when contracted naturally.

The earliest written descriptions of variolation come from China and India. In China, accounts dating to the 16th century describe a procedure known as nasal insufflation, in which physicians would grind dried smallpox scabs into a powder and blow it through a pipe into the patient’s nose. By the 18th century, a method known as scarification, involving the transfer of smallpox material into small punctures introduced in the skin, likely was employed in India. In 1721–22, variolation was popularized in England by Lady Mary Wortley Montagu, who was the wife of the British ambassador to the Ottoman Empire. While living for a time in Turkey, she learned of the practice and advocated for its use upon her return to England. In America, Cotton Mather learned of variolation in Africa from his slave, Onesimus, who himself had been inoculated. Its use spread in America after 1721, and in 1728 it was introduced into South America.

Though variolation helped reduce smallpox deaths, it still carried risks, as recipients could develop full-blown smallpox and spread the disease. Thus, variolation continued to be opposed by most physicians, as well as some religious groups. In 1796, English physician Edward Jenner discovered that cowpox infection could protect against smallpox with fewer risks. Jenner’s use of cowpox inoculation (vaccination) replaced variolation and became the foundation of modern immunization. In 1842 an act of Parliament in England made the practice of variolation a felony in that country.

In 1980, smallpox was officially eradicated, thanks to global vaccination efforts led by the World Health Organization (WHO). Learn more about diseases for which vaccines are available in this List of Vaccine-Preventable Diseases.